Engine cooling system control apparatus for vehicles and method thereof

ABSTRACT

An engine cooling system control apparatus for vehicles and a method thereof, wherein an operating load is determined by a throttle position of an engine and engine RPM, a pre-set temperature is determined in response to the operating load, and the pre-set temperature and the engine temperature are compared to control the opening and closing level of an electronic valve means for adjusting the circulating flow of cooling water, whereby the flow of cooling water can be accurately adjusted in response to the operating load condition and temperature of the engine, thereby ensuring optimal control of the cooling water temperature in response to the load condition of the engine and preventing thermal shock and instability in the cooling water temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of Korean Application No.10-2003-0065368, filed on Sep. 20, 2003, the disclosure of which isincorporated fully herein by reference.

FIELD OF THE INVENTION

The present invention relates to an engine cooling system controlapparatus for vehicles and method thereof and, more particularly, to anengine cooling system control apparatus for vehicles and method thereofconfigured to optimally control a coolant temperature and to preventthermal shock of a cooling system.

BACKGROUND OF THE INVENTION

Generally, water-cooled cooling systems for vehicles are configured suchthat engine cooling water is ejected from a water pump to sequentiallypass through a cylinder block of an engine and a cylinder head to absorbheat from the engine, and is discharged via an outlet in the cylinderhead to pass through a heater or a radiator for transfer of the heat.The cooling water is again introduced into the cylinder block via thewater pump for circulatory cooling operation. Furthermore, an outlet ofan engine is equipped with a thermostat that opens and closes inrelation to the cooling water temperature to switch a circulatory routeof cooling water.

However, there are drawbacks to the cooling system according to theprior art thus described in that a circulatory route of cooling water isswitched with a predetermined temperature as a starting point regardlessof the load condition of the engine. The prior art cooling system causesa sudden flow of water when the thermostat opens to allow cooling waterflow through the engine, resulting in a cooling water temperature dropfor a preset time, making it impossible to control the cooling watertemperature at a constant optimal level and causing thermal shock. Thissudden opening and closing of the thermostat also creates inaccuracy inmeasuring cooling water temperature.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide an engine cooling systemcontrol apparatus for vehicles and a method thereof configured tooptimally control cooling water temperature in response to the loadcondition of an engine and to prevent a thermal shock and inaccuracy inmeasuring cooling water temperature.

In accordance with a preferred embodiment of the present invention, anengine cooling system control apparatus in an engine cooling systemconfigured to pump cooling water from a water pump to sequentially passthrough an engine and a radiator for cooling the engine, compriseselectronic valve means for adjusting the amount of cooling watercirculating via the radiator. A thermometer detects the temperature ofthe cooling water as it leaves the engine. A controller controls theoperation of the electronic valve means in response to the cooling watertemperature detected by the thermometer to maintain an establishedtarget temperature.

In accordance with another embodiment of the present invention, themethod for controlling an engine cooling system for vehicles configuredto pump cooling water from a water pump to sequentially pass through anengine and a radiator for cooling the engine, comprises: (a) determiningan operating load in response to a throttle position of an engine andengine revolutions per minute (RPM); (b) determining a pre-settemperature in response to the operating load; (c) comparing the pre-settemperature with a cooling water temperature; and (d) controlling theoperation of the electronic valve means in response to the comparativeresult of the two temperatures to control the amount of circulatingcooling water.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate an embodiment of the invention,and together with the description, serve to explain the principles ofthe invention.

FIG. 1 is a schematic drawing of an engine cooling system for vehiclesaccording to an embodiment of the present invention; and

FIG. 2 is a flow chart illustrating the operating process of thecontroller of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment of the present invention will now be describedin detail with reference to the accompanying drawings.

A preferred embodiment of an engine cooling system for vehicles, asillustrated in FIG. 1, includes a first circulatory route whereincooling water of an engine 2 is pumped from a water pump 1 to passthrough a cylinder block and a cylinder head of the engine forabsorption of heat generated by the engine 2. The cooling water thenpasses through a heater core 3 and is introduced into the water pump 1.The preferred embodiment includes a second circulatory route wherein thecooling water is pumped from a water pump 1 to pass through a cylinderblock and cylinder head for absorbing the heat of the engine and thenpasses through a radiator 4 for discharging the heat. Finally, thecooling water is re-introduced into the cylinder block of the engine 2via the water pump 1.

In the first circulatory route, the cooling water flows at all times,and the amount of cooling water circulating therein is so little thatthe effect on cooling water temperature is minimal. Meanwhile, theamount of cooling water flowing in the second circulatory route isadjusted by electronic valve means 10, 11 and 12.

The radiator 4 includes cooling fan means 5 for blowing air when thecooling water exceeds a predetermined temperature to improve a heatexchange performance of the radiator 4, and an outlet thermometer 6 fordetecting the temperature of the cooling water at an outlet side of theengine 2 to produce a temperature signal. A controller 20 controls theelectronic valve means 10, 11 and 12, where the electronic valve meansincludes a valve 10, a motor 11 and a motor driving part 12.

The valve 10 is operated by application of power, generated by the motor11.

For example, the motor 11 is preferably a stepping motor where detectionof rotating position is unnecessary and a rotor is moved to apredetermined position in response to an input signal. The motor drivingpart 12 applies power to the motor 11 in response to a signal from thecontroller 20 and drives the motor.

The controller 20 determines the operating load of the engine 2 inresponse to a throttle position value input from a throttle positionsensor (not shown) of the engine 2 and an engine RPM detection valueinput from a tachometer (not shown), and determines the temperature ofcooling water at an outlet side of the engine 2 in response to atemperature signal input from the outlet thermometer 6.

Furthermore, the controller 20 determines the circulatory route of thecooling water and the valve 10 opening level in response to theoperating load thus determined and the cooling water temperature at theoutlet side to generate a control signal for operating the valve 10 inresponse thereto and sends the control signal to the motor driving part12.

The control signal generated by the controller 20 is preferably a PulseWidth Modulation (PWM) signal.

Next, the operating process of the present invention thus constructedwill be described with reference to the accompanying drawings, where Sdenotes a step.

First, the controller 20 calculates the throttle position value inputfrom the throttle position sensor (not shown) of the engine 2 and theengine RPM value input from the engine tachometer (not shown) to obtainan operating load value of the engine 2 (S10), and determines whetherthe operating load of the engine 2 is a pre-set full load operatingcondition or a pre-set intermediate load operating load (S20).

As a result of the determination at S20, if the operating load is thefull load operating condition, the controller 20 determines a targettemperature as a first set temperature (T1) (e.g., approximately 90degrees Celsius) and detects a current cooling water temperature at theoutlet side of the engine 2 in response to a signal input from theoutlet thermometer 6 to compare same with the first set temperature (T1)(S30).

If the cooling water temperature is below the first set temperature (T1)as determined by the comparison at S30, the controller 20 maintains thevalve 10 in a closed position and the cooling fan means 5 in an OFFstate, as the cooling water temperature is relatively low and there isno need for circulation of the cooling water through the radiator 4(S40).

If the current water temperature is higher than the first settemperature (T1) as determined by the comparison at S30, the controller20 generates a control signal to the motor driving part 12 to drivemotor 11 to open the valve 10 to a pre-set valve opening level (A), anddrives the cooling fan means 5 at a low speed (S50), where flow advancesto a below-mentioned valve opening and closing level proportionalintegral (PI) control step (S80).

The motor driving part 12 activates the motor 11 in response to thecontrol signal of the controller 20 to thereby open the valve 10 to anopening level A. The opening level of the valve 10 causes the coolingwater in the engine to be discharged from the water pump 1, and thecooling water sequentially passes through a cylinder block and cylinderhead of the engine 2 for absorbing the heat of the engine. The coolingwater is discharged via an outlet of the cylinder head to discharge theheat via the radiator 4, and is again introduced into the cylinder blockof the engine 2 via the water pump 1 for circulatory cooling.

By way of reference, the valve opening and closing level A is a pre-setvalue having a smaller amount of cooling water circulating than that ofthe valve opening and closing level B (described later).

Meanwhile, as a result of the determination at S20, if the operatingload condition of the engine 2 is not the full load operating conditionbut an intermediate load operating condition, the controller 20 choosesa target temperature as a second set temperature (T2, e.g., 110 degreesCelsius) and detects a current cooling temperature at the outlet side ofthe engine 2 in response to the signal from the outlet thermometer 6 tocompare same with the second set temperature (T2) (S60).

If the current outlet temperature of the engine 2 is below the secondset temperature (T2) as determined by the comparison at S60, thecontroller 20 maintains the valve 10 in the closed position, where theflowchart advances to S40 for maintaining the OFF state of the coolingfan means 5 because the cooling temperature is relatively low andcooling water circulation is not required.

As a result of the comparison at S60, if the current outlet temperatureof the engine 2 is higher than the second set temperature (T2), thecontroller 20 generates a control signal for opening the valve 10 to apre-set valve opening and closing level to send same to the motordriving part 12, and simultaneously drives the cooling fan means 5 at alow speed (S70), where the flowchart advances to the below-mentionedvalve opening and closing level (PI) control step (S80).

The motor driving part 12 drives the motor 11 in response to the controlsignal from the controller 20 to open the valve 10 up to the valveopening and closing level (B), and the cooling water of the engine isforced out from the pump 1 in response to the opening level of the valve10. The cooling water then sequentially passes through the cylinderblock and the cylinder head to absorb the heat of the engine. Thecooling water is then discharged via the outlet of the cylinder head todischarge the heat via the radiator 4 and is returned to the cylinderblock of the engine 2 via the water pump 1 to carry out the circulatorycooling process.

By way of reference, the valve opening and closing level B is largerthan the aforementioned valve opening and closing level A in terms ofallowing flow of cooling water.

Next, the controller 20 accurately increases or reduces the valveopening and closing level via a PI control that uses the current enginetemperature and the pre-set temperature (T1 or T2) as input parameters,whereby the cooling water temperature can be optimally maintained tomeet the targeted pre-set temperature (T1 or T2) (S80).

At the same time, the controller 20 compares the current coolingtemperature with a summed-up value where the pre-set temperature (T1 orT2) is added to a pre-set temperature aggravated value (e.g.,approximately 30 degrees Celsius) (S90).

As a result of the comparison at S90, if the current cooling watertemperature is larger than the summed-up value, the controller 20rotates the cooling fan means 5 at a high speed to increase the heatexchange performance of the radiator 4 because the current cooling watertemperature is fairly high, necessitating greater cooling performance(S100).

As a result of the comparison at S90, if the current cooling temperatureis below the summed-up value, the controller 20 re-compares the currentcooling temperature with the first set temperature (T1) (S110).

As a result of the comparison at S110, if the current coolingtemperature exceeds the first set temperature (T1), the controller 20returns to the valve opening and closing level PI control step (S80),and if the current cooling temperature is less than the first settemperature (T1), the flowchart returns to S10 for determining theoperating load.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purpose, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

As apparent from the foregoing, there is an advantage in the enginecooling system control apparatus for vehicles and a method thereof thusdescribed according to the present invention in that cooling water flowcan be accurately adjusted in response to operating load conditions andtemperature of an engine, thereby allowing optimal control of coolingwater temperature in response to the load conditions of the engine andpreventing thermal shock and instability in cooling operation.

1. An engine cooling system control apparatus for vehicles configured toprompt a pump cooling water to sequentially pass through an engine and aradiator for cooling the engine, wherein the engine cooling systemcontrol apparatus comprises: an electronic valve means for adjusting theamount of cooling water circulating via the radiator; a thermometer fordetecting the temperature of the cooling water having passed through theengine; and a controller for controlling operation of the electronicvalve means in response to comparing the cooling water temperaturedetected by the thermometer with an established target temperature. 2.The apparatus as defined in claim 1, wherein said electronic valve meanscomprises: a valve the operation of which adjusts the amount of coolingwater circulating via the radiator; a motor for transmitting power tosaid valve to activate the valve; and a motor driving part for applyingpower to the motor to drive the motor in response to a control signalfrom the controller.
 3. The apparatus as defined in claim 1 furthercomprising: a throttle position sensor for detecting the throttleposition of an engine; and an tachometer for measuring engine RPM,wherein the controller determines an engine load condition in responseto the throttle position detected by the throttle position sensor and anengine RPM measured by the tachometer to determine a target set-uptemperature in response to the determined engine load condition.
 4. Theapparatus as defined in claim 1 further comprising cooling fan means forcooling the radiator, wherein the controller drives the cooling fanmeans in response to the cooling water temperature and adjusts the speedof the cooling fan means.
 5. The apparatus as defined in any one ofclaims 1 to 4, wherein the controller determines a valve opening andclosing level via proportional integral control using a measured enginecooling water temperature and a target pre-set temperature as inputparameters.
 6. A vehicle engine cooling system control method configuredto pump cooling water from a water pump to sequentially pass through anengine and a radiator for cooling of the engine, wherein the vehicleengine cooling system control method comprises: determining an operatingload in response to the throttle position of an engine and engine RPM;determining a pre-set temperature in response to the operating load;comparing the pre-set temperature with actual cooling water temperature;and controlling the valve opening and closing level of said valve meansin response to the comparative result of the two temperatures to controlthe flow of circulating cooling water.
 7. The method as defined in claim6, wherein the valve opening and closing level is carried out by aproportional integral control using the actual cooling water temperatureand the pre-set temperature thus determined as input parameters.
 8. Themethod as defined in claim 6 further comprising a step of adjusting acooling fan speed for cooling a radiator and adjusting the speed of thecooling fan in response to the cooling water temperature, wherein thecooling fan speed adjusting step further comprises a step of adjustingthe cooling fan speed in response to the comparative result of thecurrent cooling water temperature and a value determined by the set-uptemperature determining step and the pre-set temperature value.